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TBIII or T88 for a M&T joint

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Forum topic by harum posted 08-24-2018 12:37 AM 596 views 0 times favorited 6 replies Add to Favorites Watch
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harum

364 posts in 2063 days


08-24-2018 12:37 AM

While working on M&T joinery for a bench, I realized that in some butt joints the walls of mortises are endgrain and tenon cheeks are long grain, like in a stretcher-to-leg joint. Even if my M&Ts have a decent tight fit, would it be safer to use an epoxy adhesive, like System Three T-88, instead of Titebond III to strengthen the endgrain to long grain bond for a long term use-and-abuse? Or is this where several dowels will be stronger that a M&T?

The manufacturer of T-88 says that:
“The adhesive may be used without modifications in normally fitted joints, and will cure in any thickness without shrinkage. T-88 is clear amber and becomes virtually invisible when varnished.”

Doesn’t it mean that it would be superior to TBIII in terms of long term stability/strength for any grain directions in gluing surfaces?

Would appreciate any comment!
Best wishes, h.

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."


6 replies so far

View TheFridge's profile

TheFridge

10858 posts in 1906 days


#1 posted 08-24-2018 01:02 AM

I wouldn’t worry too much.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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harum

364 posts in 2063 days


#2 posted 08-24-2018 02:24 AM

Well, this is my first project where joinery strengh will be actually tested daily and will have to support hundreds of pounds of weight. Besides, I should have said that while my M&Ts are tight, the tenon cheeks and mortise walls are not anywhere near hand-plane smooth; some patches feel pretty rough. Therefore, the actual gluing surface might be smaller.

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View bondogaposis's profile

bondogaposis

5454 posts in 2771 days


#3 posted 08-24-2018 03:18 AM

Epoxy has gap filling properties, where as TBIII does not. So from the information you have given I’d go with the epoxy. However not knowing how or what you are building there might be a better way to construct your joinery. It is always better to rely on the joinery rather than glue for strength.

-- Bondo Gaposis

View Woodknack's profile

Woodknack

12843 posts in 2800 days


#4 posted 08-24-2018 03:46 AM

I would use tb3 and pin the tenons. I pin all mine.

-- Rick M, http://thewoodknack.blogspot.com/

View harum's profile

harum

364 posts in 2063 days


#5 posted 08-24-2018 03:49 AM


However not knowing how or what you are building there might be a better way to construct your joinery. It is always better to rely on the joinery rather than glue for strength.

- bondogaposis

This is just an entryway bench with splayed legs, 18” high, wide enough for two people. Yes, the joinery so far is pretty tight, even without glue. However, not sure how cross-grain and engrain to long grain gluing is going to hold long term with racking, sagging, etc.

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View Brian Ellis's profile

Brian Ellis

4 posts in 335 days


#6 posted 08-24-2018 03:57 AM

This is on my kitchen table, walnut leg and spreader, oak wedge. Tight as can be with just friction.

Of course it was the first one I did and my dimensions are to say the least, loose.

-- Brian, Glendale CA

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